- Scientists have discovered the specific neurons that incite cravings
- Dopamine D1 receptors are part of a 'go' pathway in the brain
- When D1 neurons are stimulated they compel you to perform an action
- By suppressing D1 neurons experts suppressed the compulsion to drink
A cure for
alcoholism could become a reality, scientists say, after they discovered
the specific brain cells responsible for inciting cravings.
As well as helping those blighted by a weakness for alcohol, the breakthrough could help people battling a range of addictions.
Alcohol
consumption alters the structure and function of neurons in the
dorsomedial striatum, a part of the brain known to be important in
goal-driven behaviours, researchers at Texas A&M College of Medicine
found.
Dr
Jun Wang, lead author of the study, said:
'Alcoholism is a very common
disease but the mechanism is not understood very well.'
But, the findings of their study have led Dr Wung and his team a little closer to achieving that understanding. Using
an animal model, researchers determined that alcohol actually changes
the physical structure of medium spiny neurons, the main type of cell in
the striatum.
These neurons can be thought of like a tree, with many branches and small protrusions, or spines, coming off them.Each neuron has one of two types of dopamine receptors, D1 or D2 - and so can be classed as either D1 or D2 neurons.
D1 neurons are informally called part of a 'go' pathway in the brain, while D2 neurons are in the 'no-go' pathway.In other words, when D2 neurons are activated, they discourage action - telling you to wait, to stop, to do nothing.
While
it is well known that the neurotranmitter dopamine is involved in
addiction, this study reveals it is the dopamine D1 receptor that plays
an important role in addiction.
Researchers
discovered that consuming large amounts of alcohol triggers D1 neurons,
making them more excitable, which means they activate more readily with
less stimulation.
Dr Wang said: 'If these neurons are excited, you will want to drink alcohol. You'll have a craving.'
That
is to say, when neurons with D1 receptors are activated, they compel
you to perform an action reaching for another bottle of tequila, in
this case. This then creates a cycle, where drinking causes easier activation, and activation causes more drinking.
The
changes in activation of D1 neurons may be related to the physical
changes happening at a sub-cellular level in the brains of people
exposed to alcohol.If these neurons are excited, you will want to drink alcohol. You'll have a craving Dr Jun Wang
Those
people have longer branching and more mature, mushroom-shaped spines
branching from the neurons - the type that stores long-term memories -
than their abstaining counterparts. Conversely,
the placebo group, the ones not exposed to alcohol, tended to have more
of the immature versions of the mushroom-shaped spines in D1 neurons of
their brains.
The
total number of spines didn't change in the two groups, but the ratio
between mature and immature was dramatically different between the
alcohol group and the placebo group. This has important implications for memory and learning in drug addiction.
Dr Wang said: 'When you drink alcohol, long-term memory is enhanced, in a way.
'But this memory process is not useful - in fact, it underlies addiction since it affects the 'go' neurons.' Because
there was no difference in the number of each type of spine in the D2
(no-go) neurons of alcohol-consuming and control models, the researchers
realised there was a specific relationship between D1 neurons and
alcohol consumption.
'We're now able to study the brain at the neuron-specific and even spine-specific level,' Dr Wang said.
By:Dailymail.
